MKV Subtitles Not Showing: Find the Track Type, Then Pick the Fix

Step one: is there a subtitle track at all?

An MKV is a container that can hold any number of subtitle tracks, or none. Before changing settings, confirm a track exists. In VLC, open the Subtitle menu during playback and look at the Sub Track list; in other desktop players, look for a subtitles or tracks menu. You can also open the file in the free extract subtitles tool, which lists every subtitle track in your browser with its codec, language, title and default or forced flags, without uploading the video.

• No subtitle tracks listed. The file has none. If subtitles appeared elsewhere, they came from a separate file, a streaming service, or were burned into a different copy. This is not a playback fault.
• One or more tracks listed. Note each track's type, because that decides everything below.

The track types and what they mean for playback

Matroska stores each subtitle track with a codec ID. MKVToolNix's mkvextract documentation shows how differently they behave: simple text tracks come out as SRT files, SSA and ASS tracks as SSA or ASS files, WebVTT tracks as WebVTT, while PGS tracks come out as SUP files and VobSub tracks as SUB plus IDX files, which are images rather than text.

Text (S_TEXT/UTF8)

Plain timed text, equivalent to SRT. The most widely supported; the easiest to fix

ASS or SSA

Text with styles, positions, fonts and effects. Many players show the words but ignore or mangle styling; some TVs skip the track

WebVTT

Text, as used on the web. Less common inside MKV

PGS (S_HDMV/PGS)

Bitmap images from Blu-ray discs. Sharp, but many TVs, sticks and phone apps don't render them inside MKV

VobSub (S_VOBSUB)

Bitmap images from DVDs, lower resolution. Similar support gaps to PGS

Diagnose by symptom

• Shows on the computer, not on the TV or stick. The device's player doesn't render that track type, most often PGS or ASS, or it ignores embedded tracks altogether.
• Track exists but nothing shows until you pick it manually. The track's default flag is off, or your player's language preferences skip it.
• Only a handful of lines ever appear. You've selected a forced track, which only contains subtitles for foreign-language dialogue or signs. The full track is a separate one; forced subtitles explains how the flag works.
• Subtitles appear in plain text where signs and songs should be styled, or in the wrong place. The player is reading an ASS track without full ASS rendering, or without the fonts attached inside the MKV.
• Subtitles vanished after converting the MKV to MP4. The converter dropped them. Many converters only carry picture and sound, including mydubly's own MKV to MP4 converter, so extract subtitles before converting.
• An SRT file beside the MKV is ignored. That's a sidecar problem (naming, encoding, structure), covered in SRT file not working.

Fixes for text tracks

1. Select the track. In VLC, Subtitle then Sub Track; on TVs and sticks, usually the subtitle or options menu during playback. Some devices remember subtitles as off from the last video.
2. Make it the default. If you want the track to appear automatically, the default flag needs to be on. MKVToolNix's header editor can change default and forced flags without rewriting the video; alternatively, set a preferred subtitle language in your player.
3. Give TVs and phones a sidecar. Many TV and phone players handle a sidecar SRT more reliably than an embedded track. In the extract subtitles tool, choose the track and save it as SRT (or VTT), name it exactly like the MKV, and keep both in the same folder. Several tracks download together as a ZIP.
4. Flatten ASS for players that choke on it. Extract the ASS track as ASS or SRT, or run an existing .ass file through the ASS to SRT converter. It keeps the text and timing, drops styling, skips drawing commands and comment lines with a count in a note, and flags lines that were positioned on screen so you can check signs and titles.
5. Burn it in for devices that won't cooperate. Extract the track to SRT, then open the video in the free subtitle editor, import the SRT and render an MP4 with the subtitles drawn into the picture. The editor opens MKV files but doesn't read the subtitle tracks inside them, which is why the extraction step comes first.

Fixes for image tracks (PGS and VobSub)

Image subtitles are the hardest case, because there are no letters to convert. The extract tool lists these tracks so you can see them, but it can't save them as SRT; that would need OCR (optical character recognition), which it doesn't do.

• Play the file in a player that renders PGS. Desktop players such as VLC generally do; this is often the quickest answer for a computer.
• Look for a text version of the same subtitles. If a matching SRT exists for your exact release, use it as a sidecar.
• Run OCR in a desktop subtitle editor. Tools such as Subtitle Edit can read PGS or VobSub images and turn them into SRT text, which you then proofread, because OCR confuses characters such as l, I and 1.
• Burn the image track in with desktop software that can read it, such as HandBrake. The output plays everywhere but the subtitles can't be turned off.

Two examples

What can't be fixed

• Image subtitles can't be extracted as text without OCR, and OCR output always needs proofreading.
• ASS styling, karaoke timing and positioned signs can't survive conversion to SRT. They survive only in a player with full ASS rendering, or if burned in by software that renders ASS. mydubly's editor burns one style for the whole video, so it reproduces the words, not the original typesetting.
• A device that ignores embedded subtitles entirely won't be changed by any flag; only a sidecar file or burned-in subtitles help.
• Burned-in subtitles in a different copy of the video can't be extracted at all, because they are part of the picture.

Making subtitles when the MKV has none

If the file has no subtitle track and no text version exists, the subtitle generator transcribes the speech into SRT in 100 languages at 1 credit per minute, with a 5-credit minimum per file. A 45-minute episode costs 45 credits (4.5¢). Only the audio is uploaded for the AI step and it's deleted within 30 minutes of the job finishing; the video itself stays on your device.